DIY: Removing your intake manifold. Tgv deletes, fuel line repair/upgrade, new turbo inlet.. so many things reside under the manifold.
If you are not familiar with the Subaru boxer engine the intake manifold and assorted mess of spaghetti wiring and hoses can be hard to take in. So many lines running this way and that way, endless connections, fuel lines, coolant hoses, air inlet… Just so many things. Given that so many different parts run through, around and over the manifold, you will undoubtedly find a need to remove it sooner or later.
I have removed my intake manifold to install my Perrin turbo inlet and repairing my stock fuel lines that love to leak in cold temperatures. After a few times of uninstalling it, it honestly becomes second nature. What once took me a good two hours, now it easily removed in less than an hour.
Let’s get down to the tools that will help you tackle this are: A 3/8th socket set, mostly a 8, 10, 12, 14mm sockets, 3/8th ratchet and extensions. An assorted set of pliers of various lengths for clamps and hose removal. Either a pair of hose removal pliers or a set of fuel line disconnects. All these are linked at the bottom of the post!
These are a few of my favorite tools that I use. I really love the hose removal pliers for taking out fuel lines. The fuel disconnects are quite useful and you won’t need to unbolt the fuel line clamps.
These are my stand by hand tools. I have used these sockets for the last 6 years without breaking one. I really enjoy them. The wobble extensions will help you get into those hard to reach places where there are many on your Subaru. The pliers set will help remove those tricky stuck breather hoses.
Parts you will need are whatever you may be switching out, plus…. tgv to engine gaskets and a bit of coolant to top off what will be lost.
To begin this project we will start with opening the hood and removing the battery. This most important part of this intake manifold removal is undoing any electrical connector that ties into the manifold’s wire harness and runs to the long block. A quick run down of those connectors will be cam, crank, coolant temp, knock, ocv sensors and a few others like the air pump connections and coil packs.
With our battery disconnected I usually move directly above it to the air pump assembly. Removing the air pump hose and connector. Now you can undo the two bolts that attach it to the car and it is free to reside outside the engine bay. Two of the main harness connections are between the air pump and the battery and you can disconnect these at this time.
We will move to the belt system. Loosening the belt tensioners on both the A/c belt and power steering. Allowing us to remove the tension and the belts. With both belts removed you can now remove the A/c tensioner bracket assembly and set it to the side. Having removed the belts you can now undo the Alternator, start with the electrical connectors on top, then removing the bolt that runs through the power steering belt adjuster and A/c bracket.
The A/c compressor can now be disconnected and the four bolts that hold it to the engine can be freed. I You can now slide it to a place near the battery tray. Taking care that you don’t damage any of the A/c lines causing a freon leak.
Moving to the passenger side of the car I disconnect the air box from the turbo inlet and then remove the maf sensor connection and air box assembly. Only two bolts hold the box in place and are accessed with a extension.
You can now disconnect the the electrical connections on the passenger side of the car near the strut tower. There are two engine ground and one is located near these connections. If has a quick disconnect you can use to leave one side on the manifold and other side connected to the chassis. The other ground is found near the battery.
Next up we can remove the Upper coolant reservoir. I generally leave the cap on and only remove the hose that connects to a hardlines that runs through the manifold between cylinder 1 and 3. If you have a rubber grommet you can pop it over the hardline to keep coolant leakage to a minimum. I generally flip the coolant reservoir over and rest it near the passenger side strut tower. During this time you can remove the rubber hose that runs from the factory boost solenoid and turbo inlet. Set it off towards the passenger strut tower and out of the way.
As you remove the upper coolant tank you will notice the connections for the power steering lines. These need to be disconnected and pulled towards the passenger fender. There is only one nut that holds the hardlines to the bracket.
The intercooler will need to come off and you can follow my write up on that here. The quick version is to disconnect the turbo and throttle body hoses, along with the breather lines. Removing the two bolts that mount to the brackets and then the two bolts that hold the Bpv on. You can now set the intercooler to the side.
Having removed the intercooler there are two coolant lines that run into the throttle body that need to be released. They both reside on the driver’s side and will pump out a bit of coolant. One trick is to pop a bolt the same size in after removing the lines. Once again minimizing coolant loss. In vicinity you can disconnect the Pcv assembly from either the block or the manifold. I prefer the block as it is easy to put back on later.
This is a good time to loosen the turbo inlet clamp to the turbo while you are in the neighborhood. There is one breather hose from the passenger side valve cover that needs to be disconnected from the hard line on the right side of the inlet.
I tend to do the fuel lines as late as I can to help relieve the pressure. Remove the feed, return and evap line from the driver’s side hardlines. The brake booster vacuum hose is located near these and can be disconnected from the manifold.
With all openness and access I generally sweep from one side to the other removing connections. Passenger side cam sensor, Pass. Ocv connector, cylinder 1 and 3 coil packs, P/s pump sensor, coolant temp, oil pressure, crank sensor, driver’s side ocv, cam sensor and cylinder 2 and 4 coil packs. Then on the backside of the manifold, driver’s side there is an air pump connection and the knock sensor. I like to rest any wiring I can on top of the manifold to visually see it has been disconnected. This helps you from second guessing of breaking a wire.
Only 8 total bolts hold the manifold through the Tgvs and to the engine block. Each side has one bolt up front two in the center and one on the backside. Remove them all and you can now began Pull this monstrosity up. Taking care as the P/s hardlines on passenger side of the block likes to hang up and the breather lines will try and obstruct anything you do. Now is the time to double check that all the associated hoses and wiring that connects the engine to the manifold are disconnected. If they aren’t you might be looking at some wiring repair or replacement coolant lines. Lift and watch for areas that are rising unevenly. That will show you the source of the problem and you can disconnect and act like everything is fine. Take your time to not cause yourself further work and headaches.
Congratulations! You can now say you have removed an intake manifold from a Subaru and never think about doing that again. You can now add your sweet Tgv deletes, turbo inlet, injectors, repair your fuel lines or whatever your Subaru needs! Reversing the process should get you a running car again.